Many pyrrolidines are powerful inhibitors of glycohydrolases, enzymes responsible for cleavage of glycosidic bonds, glycoprotein processing and the gastrointestinal breakdown of dietary carbohydrates. These compounds are charged at physiological pH and are believed to associate with acidic amino acids at the active site. Inhibition of glycohydrolases could be of therapeutic value for the treatment of viral infections, cancer, diabetes, and obesity.